1. A crazy mothafucka and the best cornerback in the game of football. Open your mouth and I'll shut if for you real quick
2. Being a complete asshole to an opposing player after a hard-fought game/ taunting an opposing player (shermaning)

ex: After being scored on for three touchdowns by a wide receiver, the player shermaned as he taunted the receiver after his team came back to win the great game. (Richard Sherman)